1. Field of the Invention
The present invention relates to image pick-up apparatuses and in particular, though not exclusively, relates to an image pick-up apparatus having a mirror unit arranged on an optical path between an object and an image capturing device.
2. Description of the Related Art
In a single lens reflex camera, an example of an image pick-up apparatus, during observing an object using an optical finder, a luminous flux emitted from a taking lens is reflected by a reflection mirror arranged adjacent to an image plane from the taking lens and introduced to the optical finder including a pentacle prism. Thereby, a picture taker can observe an object image formed by the taking lens as an elect image. At this time, the reflection mirror is obliquely arranged on the optical path.
On the other hand, in order to take a picture of the object image, the luminous flux from the taking lens is allowed to reach an image pick-up medium (e.g., in the image capturing device e.g., a film and a CCD) by moving the reflection mirror from the optical path. Upon completion of taking a picture, the reflection mirror is obliquely arranged on the optical path.
In a single lens reflex camera having a pellicle mirror, there can be a camera capable of taking a picture by allowing a luminous flux which has transmitted through the pellicle mirror to reach an image capturing device or a film without moving the pellicle mirror even when a picture of an object image is taken.
In the camera discussed in Japanese Patent Laid-Open No. H08-254751, taking a picture by moving the pellicle mirror away from the optical path and taking a picture without moving the pellicle mirror are used depending on imaging conditions, and when taking a picture without moving the pellicle mirror, it is characteristic of the conventional camera to not darken a finder image and to operate quietly even during releasing a shutter.
Conventional single lens reflex digital cameras typically include a camera capable of switching between a state where the luminous flux from the taking lens is divided into a finder optical system and a phase-difference detection AF unit for detecting focusing, and a state where the luminous flux from the taking lens is divided into the image capturing device and the phase-difference detection AF unit for detecting focusing. In the camera discussed in Japanese Patent Laid-Open No. 2004-264832, the state where the luminous flux from the taking lens is divided into the finder optical system and the AF unit, an object image can be observed using an optical finder. In the state where the luminous flux from the taking lens is divided into the image capturing device and the AF unit, an object image can be observed using an electronic finder driven by an output from the image capturing device with a display unit arranged on the camera back face. Also, even when any one of the optical finder and the electronic finder is set, high-speed auto focusing can be executed by introducing part of the luminous flux from the taking lens to the phase-difference detection AF unit.
Recently, a market need has arisen for a moving image capturing function for single lens reflex cameras; however, conventional single lens reflex cameras which capture images by moving a reflection mirror are structurally difficult to pick up moving images. Thus, a camera discussed in Japanese Patent Laid-Open No. 2004-264832 is constructed to have three positions of a mirror unit, including one for taking a moving picture as well as automatically focusing in a phase-difference system.
Furthermore, another desired feature is to record only a specific scene in still images during capturing moving images. For instance, for a footrace of school athletic meets, during shooting moving images, it might be desirable to also obtain the finishing line still image of a runner, while the moving images are captured. For example, using the camera configuration in Japanese Patent Laid-Open No. 2004-264832. Because of the need for switching between modes of moving image pick up (also herein referred to as the moving image picking up) and still image pick up (also referred to herein as the still image picking up), a predetermined period of time can be required for the switching, so that a picture taker may miss a shutter chance.
Also, the single lens reflex camera having a pellicle mirror and discussed in Japanese Patent Laid-Open No. H08-254751 has a problem that a plurality of imaging modes cannot be continuously switched such that a still image cannot be picked up during taking moving images.